An MP has launched a stinging attack on a key architect of the Northern Powerhouse for voicing scepticism about pan-Yorkshire devolution, describing him as a dinner circuit “raconteur” who no longer has influence in Westminster.

Keighley MP John Grogan accused former Treasury Minister Lord Jim O’Neill of “grossly underestimating” the power of the Yorkshire brand to bring investment into the region.

Lord O’Neill, a key ally of George Osborne in efforts to empower the North, had criticised supporters of a “One Yorkshire” deal for “repeated focus on the marketing brand of the name Yorkshire” using “chest-beating slogans” rather than making the economic case for getting money and powers from Westminster.

Leeds City Council leader Judith Blake also hit back at Lord O’Neill, saying the One Yorkshire proposal has “moved on considerably” in recent months.

“We have made a submission to government and started negotiations with them based on the significant benefits for the economy of the whole of Yorkshire. Indeed our proposal makes it clear how devolution could double the size of Yorkshire’s economy over the next 30 years.

“I appreciate Lord O’Neill has many ties to Manchester and the North West, but it’s important to understand how this differs from the position here in Yorkshire.”